Abstract:

Infectious diseases including Newcastle disease are considered among important factors responsible for huge losses to poultry farmers and vaccination has been considered effective and affordable control option. Conventional vaccine delivery methods are not suitable for smallholder and rural poultry producers. This study was carried out with the aim of evaluating the efficacy of NDI2 vaccine delivered via drinking water and litter spray compared to standard eye drop method under smallholder farmers’ condition between December 2016 and May 2017. Molecular diagnosis of Newcastle disease was also conducted using RT-PCR targeting the L gene of Newcastle disease virus RNA. Twenty households rearing 154 chickens (82 indigenous and 72 exotic breeds) were selected purposively. The selected households were randomly assigned to one of the four treatments groups: placebo, drinking water, eye drop and spray. Blood samples were collected and HI assay was conducted on individual samples. Impressions of organ samples were collected from suspected Newcastle disease cases on FTA cards for molecular analysis. At baseline, there was no significant difference in antibody titre among the experimental groups. After the first and booster vaccinations, statistically significant (P < 0.001) variation was observed in mean (log2) antibody titre between the vaccinated groups and the unvaccinated control group. Multiple pairwise comparison of mean antibody titre showed that the three experimental groups had significantly higher antibody titer than the control group after the first and booster vaccinations. Interestingly there was no statistically significant difference in antibody titre among the vaccinated groups. After the first vaccination, the proportion of chicken with antibody titre ≥ log23 was 74 %, 90% and 93% in the group vaccinated via drinking water, eye drop and spray respectively. Whereas in the control group it was 48%. After booster vaccination, the proportion of chicken with antibody titre ≥ log23 was 90 %, 90% and 93% in the group vaccinated via drinking water, eye drop and spray respectively. Whereas in the control group it remained 45%. The vaccinated group showed 100 % survival while the control group showed only 40% survival after challenge infection. Out of 11 representative samples analyzed 3 samples (27.27%) were positive for NDV RNA. The results obtained from this study shows that NDI2 vaccine administered via drinking water and litter spray under smallholder farmers’ situation provoked protective antibody level similar to the eye drop method. Use of NDI2 vaccine needs to be considered by the veterinary and livestock authorities to prevent ND outbreaks and large-scale evaluation of the NDI2 vaccine delivery routes have to be carried out.